Semiconductor device and related manufacturing method

ABSTRACT

A method for manufacturing a semiconductor device may include providing a first dielectric layer and a first set of conductive pads on a first substrate. Each conductive pad of the first set of conductive pads may be positioned between portions of the first dielectric layer. The method may further include providing a first insulating material layer to cover the first dielectric layer and the first set of conductive pads. The method may further include removing portions of the first insulating material layer to form a first insulating layer. Openings of the first insulating layer may expose the first set of conductive pads.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of Chinese PatentApplication No. 201310753305.5, filed on 31 Dec. 2013, the ChinesePatent Application being incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

The present invention is related to a semiconductor device, a method formanufacturing the semiconductor device, and a method for packaging thesemiconductor device.

In consumer electronics, multifunctional electronic devices have becomepopular. For integrating chips of various functions on a circuit boardof a multifunctional electronic device, a three-dimensional integratedcircuit (3D IC) structure may be implemented.

In a 3D IC structure, chips may be stacked vertically and may beinterconnected through leads and metal lines. The metal lines mayundesirably complicate and/or enlarge the circuit board. For simplifyingand/or minimizing a 3D IC structure, wafer-level copper-copper (Cu—Cu)bonding may be implemented.

FIG. 2 shows a flowchart that illustrates a wafer-level Cu—Cu bondingprocess. FIG. 3 shows a schematic cross-sectional view that illustratesa portion of a first wafer 10 and a portion of a second wafer 20involved in the wafer-level Cu—Cu bonding process. Referring to FIG. 2,the process may include preparing two substrates, including a firstsubstrate and a second substrate. For each of the wafers, the processmay further include the following steps: forming an interlayerdielectric layer on the substrate, forming a mask on the interlayerdielectric layer, using the mask for patterning the interlayerdielectric layer to form a recess, forming a barrier layer and a seedlayer in the recess (through deposition), forming a copper (Cu) memberin the recess through electroplating (ECP), planarizing the Cu memberthrough chemical-mechanical polishing/planarization (CMP) to form a Cupad, and cleaning the wafer that includes the Cu pad.

As a result, the first wafer 10 and the second wafer 20 illustrated inFIG. 3 may be formed. Each of the first wafer 10 and the second wafer 20may include an interlayer dielectric layer and a Cu pad embedded in theinterlayer dielectric layer. For example, the second wafer 20 mayinclude an interlayer dielectric layer 101 and a Cu pad 102 embedded inthe interlayer dielectric layer 101. Each wafer may further includeother Cu pads that are analogous to the Cu pad 102.

The wafer-level Cu—Cu bonding process may further include combining theCu pads of the wafer 101 and the Cu pads of the wafer 102 throughlow-temperature thermocompression bonding. The process may furtherinclude performing annealing on the combined structure.

Given that spaces between Cu pads may be substantially small and that Cuhas substantial ductility, as illustrated in FIG. 1B, unwantedconnections may be formed as a result of the thermocompression bonding.FIG. 1B shows a diagram that illustrates a cross-section of a portion ofa wafer combination involving face-to-face stacking of two wafers. Inthe wafer combination illustrated in FIG. 1B, unwanted connections maybe formed as a result of combining Cu pads through thermocompressionbonding. As a result, undesirable short circuits may occur insemiconductor devices that are manufactured using the wafer combination,such that the semiconductor devices may be defective.

FIG. 1A shows a diagram that illustrates a cross-section of a portion ofa wafer combination involving face-to-face stacking of two wafers. Thewafer combination illustrated in FIG. 1A may have substantially nounwanted short circuits. Nevertheless, a result of combining Cu padsthrough thermocompression bonding, defects may be formed in Cu pads ofthe wafer combination illustrated in FIG. 1A. As a result, reliabilityof semiconductor devices manufactured using the wafer combination may beunsatisfactory.

SUMMARY

An embodiment of the present invention may be related to a method formanufacturing a semiconductor device. The method may include providing afirst dielectric layer and a first set of conductive pads on a firstsubstrate. Each conductive pad of the first set of conductive pads maybe positioned between portions of the first dielectric layer. The methodmay further include providing a first insulating material layer to coverthe first dielectric layer and the first set of conductive pads. Themethod may further include removing portions of the first insulatingmaterial layer to form a first insulating layer. Openings of the firstinsulating layer may expose the first set of conductive pads.

The first insulating layer may include at least one of abenzocyclobutene material and a silicone-polymer material.

The method may include forming a first dielectric material layer on thefirst substrate. The method may further include etching the firstdielectric material layer to form the first dielectric layer. Athickness of the first dielectric layer may be less than a thickness ofthe first dielectric material layer.

The first insulating material layer may be formed on the firstdielectric layer and the first set of conductive pads through spincoating.

The openings may include a first opening. The first set of conductivepads may include a first conductive pad exposed by the first opening. Acritical dimension of the first opening of the first insulating layermay be greater than a critical dimension of the first conductive pad,such that a first gap may be provided between the first conductive padand the first insulating layer.

The first insulating layer may not directly contact the first set ofconductive pads.

A first portion of the first insulating layer may be positioned betweenat least two conductive pads of the first set of conductive pads. Asecond portion of the first insulating layer may directly contact anedge portion of the first dielectric layer. At least one conductive padof the first set of conductive pads may be positioned between the firstportion of the first insulating layer and the second portion of thefirst insulating layer. The second portion of the first insulating layermay be narrower than the edge portion of the first dielectric layer in adirection parallel to an interface between the first insulating layerand the first dielectric layer.

The step of removing the portions of first insulating material layer mayinclude the following steps: forming a mask material layer on the firstinsulating material layer, the mask material layer including at leastone of a first photoresist layer, an organic distribution layer, and asilicon-containing bottom antireflective coating; forming a patternedphotoresist layer on the mask material layer; etching the mask materiallayer using the patterned photoresist layer to form a mask; and etchingthe first insulating material layer using the mask. As a result, theopenings of the first insulating layer may be formed.

A height of the first insulating layer with respect to the firstsubstrate may be greater than a height of the first set of conductivepads with respect to the first substrate. Therefore, a bonding processinvolving the first insulating layer may precede a bonding processinvolving the first set of conductive pads.

The method may include the following steps: providing a seconddielectric layer and a second set of conductive pads on a secondsubstrate, each conductive pad of the second set of conductive padsbeing positioned between portions of the second dielectric layer;providing a second insulating material layer to cover the seconddielectric layer and the second set of conductive pads; and removingportions of the second insulating material layer to form a secondinsulating layer, opening of the second insulating layer exposing thesecond set of conductive pads; connecting the first insulating layer tothe second insulating layer; and after the connecting the firstinsulating layer to the second insulating layer, connecting the firstset of conductive pads to the second set of conductive pads.

At least one of the first insulating layer and the second insulatinglayer may be formed of benzocyclobutene. The step of connecting thefirst insulating layer to the second insulating layer may be performedat a temperature in a range of 100° C. to 150° C. for a time duration ina range of 10 minutes to 30 minutes using a pressure in a range of 30 kNto 60 kN.

At least one of the first insulating layer and the second insulatinglayer may be formed of a silicone-polymer material. The step ofconnecting the first insulating layer to the second insulating layer maybe performed at a temperature in a range of 150° C. to 180° C. for atime duration in a range of 10 minutes to 30 minutes using a pressure ina range of 30 kN to 60 kN.

The step of connecting the first set of conductive pads to the secondset of conductive pads is performed at a temperature in a range of 300°C. to 400° C. for a time duration in a range of 20 minutes to 60 minutesusing a pressure in a range of 30 kN to 40 kN.

The method may include the following steps: providing a seconddielectric layer and a second set of conductive pads on a secondsubstrate, each conductive pad of the second set of conductive padsbeing disposed between portions of the second dielectric layer;connecting the first insulating layer to the second dielectric layer;and after the connecting the first insulating layer to the seconddielectric layer, connecting the first set of conductive pads to thesecond set of conductive pads.

The first insulating layer may be formed of benzocyclobutene. The stepof connecting the first insulating layer to the second insulating layermay be performed at a temperature in a range of 100° C. to 150° C. for atime duration in a range of 10 minutes to 30 minutes using a pressure ina range of 30 kN to 60 kN.

The first insulating layer may be formed of a silicone-polymer material.The step of connecting the first insulating layer to the secondinsulating layer may be performed at a temperature in a range of 150° C.to 180° C. for a time duration in a range of 10 minutes to 30 minutesusing a pressure in a range of 30 kN to 60 kN.

An embodiment of the present invention may be related to a semiconductordevice that may include a first substrate and a second substrate. Thesemiconductor device may further include a first conductive pad and asecond conductive pad (each being a combination of two conductive padsand each being positioned between the first substrate and the secondsubstrate). The semiconductor device may further include a firstdielectric layer formed of a first material (e.g., an oxide), a firstportion of the first dielectric layer being positioned between the firstconductive pad and the second conductive pad and directly contactingeach of the first conductive pad and the second conductive pad. Thesemiconductor device may further include a second dielectric layer, afirst portion of the second dielectric layer being positioned betweenthe first conductive pad and the second conductive pad and directlycontacting each of the first conductive pad and the second conductivepad. The semiconductor device may further include an insulating layerformed of a second material different from the first material, a firstportion of the insulating layer being positioned between the firstportion of the first dielectric layer and the first portion of thesecond dielectric layer and being positioned between the firstconductive pad and the second conductive pad. The insulating layer mayrepresent a combination of two insulating layers of two combined wafersor may represent the insulating layer of one of two combined wafers. Thesecond material may include at least one of a benzocyclobutene materialand a silicone-polymer material.

The first portion of the insulating layer may be narrower than each ofthe first portion of the first dielectric layer and the first portion ofthe second dielectric layer in a direction parallel to an interfacebetween the insulating player and the first dielectric layer. The firstportion of the insulating layer may be spaced from all conductive padsof the semiconductor device and may not directly contact any conductivepad of the semiconductor device.

An edge portion of the insulating layer may be positioned at an edge ofthe semiconductor device, may directly contact each of an edge portionof the first dielectric layer and an edge portion of the seconddielectric layer, and may be narrower than each of the edge portion ofthe first dielectric layer and the edge portion of the second dielectriclayer in a direction parallel to an interface between the insulatinglayer and the first dielectric layer. The edge portion of the insulatinglayer may be spaced from all conductive pads of the semiconductor deviceand may not contact any conductive pad of the semiconductor device.

The above summary is related to one or more of many embodiments of theinvention disclosed herein and is not intended to limit the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a diagram that illustrates a cross-section of a portion ofa wafer combination involving face-to-face stacking of two wafers.

FIG. 1B shows a diagram that illustrates a cross-section of a portion ofa wafer combination involving face-to-face stacking of two wafers.

FIG. 2 shows a flowchart that illustrates a wafer-level Cu—Cu bondingprocess.

FIG. 3 shows a schematic cross-sectional view that illustrates portionsof two wafers involved in a wafer-level Cu—Cu bonding process.

FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D show schematic cross-sectionalviews that illustrate a portion of a wafer prepared for a wafer-levelCu—Cu bonding process in accordance with an embodiment of the presentinvention.

FIG. 5A and FIG. 5B show schematic cross-sectional views that illustrateportions of two wafers involved in a wafer-level Cu—Cu bonding processin accordance with an embodiment of the present invention.

FIG. 6 shows a flowchart that illustrates a method involving awafer-level Cu—Cu bonding process for combining two wafers in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION

Example embodiments of the present invention are described withreference to the accompanying drawings. As those skilled in the artwould realize, the described embodiments may be modified in variousdifferent ways, all without departing from the spirit or scope of thepresent invention. Embodiments of the present invention may be practicedwithout some or all of these specific details. Well known process stepsand/or structures may not have been described in detail in order to notunnecessarily obscure the present invention.

The drawings and description are illustrative and not restrictive. Likereference numerals may designate like (e.g., analogous or identical)elements in the specification. Repetition of description may be avoided.

The relative sizes and thicknesses of elements shown in the drawings arefor facilitate description and understanding, without limiting thepresent invention. In the drawings, the thicknesses of some layers,films, panels, regions, etc., may be exaggerated for clarity.

Illustrations of example embodiments in the figures may representidealized illustrations. Variations from the shapes illustrated in theillustrations, as a result of, for example, manufacturing techniquesand/or tolerances, may be possible. Thus, the example embodiments shouldnot be construed as limited to the shapes or regions illustrated hereinbut are to include deviations in the shapes. For example, an etchedregion illustrated as a rectangle may have rounded or curved features.The shapes and regions illustrated in the figures are illustrative andshould not limit the scope of the example embodiments.

Although the terms “first”, “second”, etc. may be used herein todescribe various elements, these elements, should not be limited bythese terms. These terms may be used to distinguish one element fromanother element. Thus, a first element discussed below may be termed asecond element without departing from the teachings of the presentinvention. The description of an element as a “first” element may notrequire or imply the presence of a second element or other elements. Theterms “first”, “second”, etc. may also be used herein to differentiatedifferent categories or sets of elements. For conciseness, the terms“first”, “second”, etc. may represent “first-category (or first-set)”,“second-category (or second-set)”, etc., respectively.

If a first element (such as a layer, film, region, or substrate) isreferred to as being “on”, “neighboring”, “connected to”, or “coupledwith” a second element, then the first element can be directly on,directly neighboring, directly connected to, or directly coupled withthe second element, or an intervening element may also be presentbetween the first element and the second element. If a first element isreferred to as being “directly on”, “directly neighboring”, “directlyconnected to”, or “directed coupled with” a second element, then nointended intervening element (except environmental elements such as air)may also be present between the first element and the second element.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's spatial relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms may encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations), and the spatially relativedescriptors used herein should be interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to limit the invention. As used herein,the singular forms, “a”, “an”, and “the” may indicate plural forms aswell, unless the context clearly indicates otherwise. The terms“includes” and/or “including”, when used in this specification, mayspecify the presence of stated features, integers, steps, operations,elements, and/or components, but may not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups.

Unless otherwise defined, terms (including technical and scientificterms) used herein have the same meanings as commonly understood by oneof ordinary skill in the art related to this invention. Terms, such asthose defined in commonly used dictionaries, should be interpreted ashaving meanings that are consistent with their meanings in the contextof the relevant art and should not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

The term “connect” may mean “electrically connect”. The term “insulate”may mean “electrically insulate”.

Unless explicitly described to the contrary, the word “comprise” andvariations such as “comprises”, “comprising”, “include”, or “including”may imply the inclusion of stated elements but not the exclusion ofother elements.

Various embodiments, including methods and techniques, are described inthis disclosure. Embodiments of the invention may also cover an articleof manufacture that includes a non-transitory computer readable mediumon which computer-readable instructions for carrying out embodiments ofthe inventive technique are stored. The computer readable medium mayinclude, for example, semiconductor, magnetic, opto-magnetic, optical,or other forms of computer readable medium for storing computer readablecode. Further, the invention may also cover apparatuses for practicingembodiments of the invention. Such apparatus may include circuits,dedicated and/or programmable, to carry out operations pertaining toembodiments of the invention. Examples of such apparatus include ageneral purpose computer and/or a dedicated computing device whenappropriately programmed and may include a combination of acomputer/computing device and dedicated/programmable hardware circuits(such as electrical, mechanical, and/or optical circuits) adapted forthe various operations pertaining to embodiments of the invention.

FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D show schematic cross-sectionalviews that illustrate a portion of a wafer prepared for a wafer-levelCu—Cu bonding process in accordance with an embodiment of the presentinvention. FIG. 5A and FIG. 5B show schematic cross-sectional views thatillustrate portions of two wafers involved in a wafer-level Cu—Cubonding process in accordance with an embodiment of the presentinvention. FIG. 6 shows a flowchart that illustrates a method involvinga wafer-level Cu—Cu bonding process for combining two wafers inaccordance with an embodiment of the present invention. The method maybe implemented for packaging semiconductor wafers (which includeintegrated circuits) and/or for manufacturing semiconductor devices.

Referring to FIG. 6, the method may include preparing a first wafer anda second wafer. The first wafer may be prepared using steps 601 to 610.The second wafer may be prepared using steps that are substantiallyanalogous to steps 601 to 610. After both the first wafer and the secondwafer have been prepared, in a step 611, the first wafer may be combinedwith the second wafer through Cu—Cu bonding, such that a wafercombination may be produced. Subsequently, in a step 612, annealing maybe performed on the wafer combination.

Referring to FIG. 6 and FIG. 4A, in the step 601, a (first or second)substrate 201 may be prepared. The substrate 201 may include activedevices and interconnection structures.

The substrate 201 may include a base substrate. The base substrate mayinclude at least one of the following materials and/or structures:silicon, a silicon-on-insulator (SOI) structure, asilicon-on-silicon-on-insulator (SSOI) structure, asilicon-on-silicon-germanium-on-insulator (S—SiGeOI), asilicon-germanium-on-insulator (SiGeOI) structure, etc.

The base substrate may be a semiconductor base substrate and may includeactive devices and interconnection structures. The semiconductor basesubstrate may include a through-silicon via (TSV) structure.

A method for forming the TSV structure may include the following steps:forming a mask layer (e.g., a hard mask layer) on a semiconductor basesubstrate material member, patterning the mask layer to form an openingin the mask layer, etching the semiconductor base substrate materialmember through the opening to form a TSV recess. The etching may beperformed using dry etching or wet etching.

The method for forming the TSV structure may further include forming anisolation layer (e.g., an insulation layer) in the TSV recess. Theisolation layer may be formed using a thermal oxidation method. Theisolation layer may be a SiO₂ layer. A thickness of the isolation layermay be in a range of 8 angstroms (Å) to 50 Å.

The thermal oxidation may be performed using a conventional rapidthermal oxidation method. For performing the thermal oxidation, O₂ or anO₂-containing atmosphere may be used in heat-treating the structure thatincludes the TSV recess. The heat treatment (or thermal oxidation)temperature may be in a range of 800° C. to 1500° C. In an embodiment,the heat treatment (or thermal oxidation) temperature may be in a rangeof 1100° C. to 1200° C. The heat treatment (or thermal oxidation) timeduration may be in a range of 2 minutes to 30 minutes. As a result ofthe heat treatment (or thermal oxidation), a TSV recess oxide layer maybe formed in the TSV recess for functioning as the isolation layer, anda base substrate oxide layer may be formed on the base substratestructure. A thickness of the TSV recess oxide layer (i.e., theisolation layer) and/or a thickness of the base substrate oxide layermay be in a range of 2 Å to 8 Å. In an embodiment, the thickness of atleast one of the oxide layers may be 5 Å.

The method for forming the TSV structure may further include filling aconductive material in the TSV recess. The conductive material may be ametal, such as copper (Cu). The conductive material may be filled in theTSV recess using a physical vapor deposition (PVD) method and/or usingan electrochemical plating (ECP) method.

The method for forming the TSV structure may further include planarizingthe conductive material that has been filled in the TSV recess. Theplanarization may be performed using a mechanical planarization methodand/or a chemical-mechanical planarization (CMP) method. As a result, aTSV base substrate that includes the TSV structure may be formed.

Subsequently, interconnection structures may be formed in the TSV basesubstrate. One or more interconnection structures may be formed on theTSV structure. One or more interconnection structures may be formed at avia on an active device, an interlayer metal layer via, and/or a top viaof the TSV base substrate. As a result, the substrate 201 may be formed.

As an example, the via on the active device may be formed using thefollowing steps: depositing an interlayer dielectric layer on thesemiconductor base substrate, patterning the interlayer dielectric layerto form an opening that exposes the active device, filling a conductivematerial in the opening, and planarizing the filled conductive material.As a result, an electrical connection to the active device in thesemiconductor base substrate may be provided. The interlayer metal layerand/or the top via may be formed using a method analogous to the methodfor forming the via on the active device. Additionally or alternatively,one or more of the vias may be formed using one or more well-knownmethods.

Subsequently, referring to FIG. 6 and FIG. 4A, in step 602, aninterlayer dielectric layer 202 material may be formed (e.g., deposited)on the substrate 201, and a mask may be formed on the interlayerdielectric layer 202 material. In step 603, the dielectric layer 202material may be etched and/or patterned through a pattern (e.g., anopening) of the mask such that a recessed dielectric layer 202 materialthat has a recess may be formed. The interlayer dielectric layer 202material may include a conventional dielectric material. In anembodiment, the interlayer dielectric layer 202 material may includeSiO₂.

The interlayer dielectric layer 202 material may be formed on thesubstrate 201 using one or more of the following methods: a chemicalvapor deposition (CVD) method, a physical vapor deposition (PVD) method,an atomic layer deposition (ALD) method, a low pressure chemical vapordeposition (LPCVD) method, a laser ablation deposition (LAD) method, anda selective epitaxial growth (SEG) method. In an embodiment, a CVDmethod may be used for depositing the interlayer dielectric layer 202material on the substrate 201.

The formation of the mask on the interlayer dielectric layer 202material may include the following steps: forming a mask material layerthat includes at least one of a first photoresist layer, an organicdistribution layer (ODL), and a silicon-containing bottom antireflectivecoating (Si-BARC) on the interlayer dielectric layer 202; forming apatterned photoresist layer on the mask material layer, wherein apattern (e.g., an opening) of the patterned photoresist layer may definea shape of the recess; and etching the mask material layer through thepattern of the patterned photoresist layer to form the mask. The maskmay have a pattern (e.g. an opening) that corresponds to a shape of therecess to be formed.

In step 603, the dielectric layer 202 material may etched and/orpatterned through the pattern of the mask such that a recesseddielectric layer 202 material that has the recess may be formed.

The shape of the recess and/or the number of recesses formed may bedetermined according to particular embodiments. In an embodiment, thecritical dimension of the upper opening of the recess may be equal tothe critical dimension of the lower opening of the recess. In anembodiment, the critical dimension of the upper opening of the recessmay be greater than the critical dimension of the lower opening of therecess.

The recess may be formed through a dry etching method and/or a wetetching method. In an embodiment, a CF etchant may be used for etchingthe dielectric layer 202 material. The C—F etchant may include one ormore of CF₄, CHF₃, C₄F₈, and C₅F₈. In an embodiment, dry etching may beperformed using CF₄, CHF₃, and at least one of N₂, CO₂, and O₂ to forman etching atmosphere, with the following gas flow rates: a CF₄ flowrate in a range of 10 sccm to 200 sccm, a CHF₃ flow rate in a range of10 sccm to 200 sccm, a N₂, CO₂, and/or O₂ flow rate in a range of 210sccm to 400 sccm. The etching pressure may be in a range of 30 mTorr to150 mTorr. The etching time duration may be in a range of 5 seconds to120 seconds. In an embodiment, the etching time duration may be in arange of 5 seconds to 60 seconds. In an embodiment, the etching timeduration may be in a range of 5 seconds to 30 seconds.

A plurality of recesses may be formed substantially simultaneously in ananalogous manner.

Subsequently, referring to FIG. 6 and FIG. 4A, in step 604, a barrierlayer and a pad material seed layer (e.g., a copper seed layer) may beformed (e.g., deposited) in the recess for forming a conductive bondingpad 203.

In step 604, a barrier layer (not shown) may be formed in the recess forpreventing potential diffusion of metal, e.g., copper (Cu). The barrierlayer may be a Cu diffusion barrier layer for preventing Cu diffusion.The barrier layer may be formed through at least one of a physical vapordeposition method and a chemical vapor deposition method. In anembodiment, the barrier layer may be formed through at least one ofevaporation, electron beam evaporation, plasma spray deposition, andsputtering. In an embodiment, the barrier layer may be formed throughplasma spray deposition and sputtering. The thickness of the copperdiffusion barrier layer may be configured according to particularembodiments. A material of the barrier layer may include one or more ofTaN, Ta, TiN, and Ti, for reducing or minimizing the RC time delaypotentially caused by parasitic resistance and parasitic capacitance. Inan embodiment, the barrier layer may be made of TaN and/or Ta.

A plurality of barrier layers may be formed substantially simultaneouslyin an analogous manner.

In step 604, after the barrier layer has been formed, a metal Cu seedlayer may be subsequently deposited inside the recess and may besurrounded by the barrier layer. The deposition of the Cu seed layer maybe performed using at least one of a chemical vapor deposition (CVD), aphysical vapor deposition (PVD) method, and an atomic layer deposition(ALD) method.

Subsequently, in step 605, a metal Cu body may be formed over the metalCu seed layer through electrochemical plating (ECP) to substantiallyfill the recess. One or more additives, such as one or more of aleveler, an accelerator, and a suppressor, may be used in the ECPprocess. In an embodiment, after the metal Cu body has been formed, anannealing process may be performed on the metal Cu body to cause Cure-crystallization and grain growth in the Cu body, for reducing theresistance of the Cu body and/or for enhancing the stability of the Cubody. The annealing may be performed at temperature in a range of 80° C.to 160° C. for a time duration in a range of 2 hours to 4 hours.

Subsequently, in step 606, planarization may be performed on the metalCu body (and the barrier layer) to obtain a bonding pad 203 that has asubstantially uniform height. The planarization may be performed throughchemical-mechanical planarization/polishing (CMP). A plurality ofbonding pads 203 may be formed substantially simultaneously in ananalogous manner. The bonding pad(s) 203 may have a larger height thanthe interlayer dielectric layer 202 and may protrude over the interlayerdielectric layer 202.

Subsequently, referring to FIG. 6, FIG. 4A, and FIG. 4B, in step 607, aportion of the recessed dielectric layer 202 material may be selectivelyetched to reduce the dielectric material layer thickness, such that theinter layer dielectric layer 202 may be formed. The etching of therecessed dielectric layer 202 material may be performed using at leastone of dry etching and wet etching.

In an embodiment, dry etching process may be performed in step 607, anda SICONI™ etch process may be performed. The SICONI™ etch process mayprovide desirable etch selectivity between the recessed dielectric layer202 material, the bonding pads 203, and the barrier layers. Specificparameters for the SICONI™ etch process may be configured according toparticular embodiments.

In an embodiment, wet etching may be performed in step 607, and theetchant may include at least one of a hydrofluoric acid (HF) and adiluted hydrofluoric acid (DHF). In an embodiment, in the etchantcomposition, HF:H₂O may be in a range of 1:2 to 1:10. The etchingtemperature may be in a range of 20° C. to 25° C.

The specific thickness of the interlayer dielectric layer 202 may beobtained through one or more alternative processes and/or one or moreadditional processes.

Subsequently, referring to FIG. 6, FIG. 4B, and FIG. 4C, in step 608, abenzocyclobutene (BCB) material layer 204 may be formed on the bondingpads 203 and the interlayer dielectric layer 202. Portions of the BCBmaterial layer 204 may be disposed between bonding pads 203, whichprotrude over the interlayer dielectric layer 202. The BCB materiallayer 204 may be formed through. The BCB material layer 204 may besufficiently photosensitive for subsequent processing. The BCB materiallayer 204 may have a substantially low stress and may have sufficientplasticity, such that the BCB material layer 204 may effectively reducethe stress in the structure illustrated in FIG. 4C. The BCB materialbonding-insulating layers 205 subsequently formed from the BCB materiallayer 204 may effectively minimize stress in associated structures.

The BCB material may have desirable adhesion with the barrier layers(e.g., oxide barrier layers) and with the bonding pads (e.g., Al padsand/or Cu pads. The BCB material may be desirably fused with underlyingdielectric layer 202. In a subsequent process of bonding two wafers, theBCB material bonding-insulating layers 205 may be desirably fused toform a substantially seamless bonding, such that the bonding quality ofthe wafers may be satisfactory. The BCB material bonding-insulatinglayers 205 may function as barrier layers to effectively preventdiffusion of conductive bonding pad material (e.g., Cu).

Embodiments of the invention may take advantage of characteristics ofthe BCB material. The BCB material is an organic material having themolecular formula C₈H₈ and can be applied through spin coating. The BCBmaterial may be capable of reflow at a temperature higher than 170° C.The BCB material may have desirable gap-filling capability, which may beimportant for devices with small critical dimensions. The BCB materialmay have a substantially low dielectric constant (K) value, forproviding sufficient electrical insulation. The BCB material may havesubstantially low stress and desirable stress-relief properties, suchthat BCB material bonding-insulating layers 205 may not be damagedduring wafer bonding, and such that edges of wafers may also bedesirably bonded. The thickness of the BCB material layer 204 and/or theheight of the BCB material layer over the dielectric layer 202 may belarger than the portions of the bonding pads 203 that protrude over thedielectric layer 202, such that the bonding pads may be substantiallycompletely covered by the BCB material layer 204.

Subsequently, referring to FIG. 6, FIG. 4C, and FIG. 4D, in step 609,the BCB material layer 204 may be patterned (e.g., etched) to removeportions of the BCB material layer that overlap (and cover) the bondingpads 203, such that the bonding pads 203 are exposed through openings207, and such that BCB material bonding-insulating layer 205 with BCBmaterial portions positioned between bonding pads 203 and/or positionedat edges of the wafer (and/or the edges of the dielectric layer 202) maybe formed.

The critical dimensions of the openings 207 may be sufficiently greaterthan the critical dimensions of respective corresponding bonding pads203. Therefore, gaps 206 (or recesses 206) may be formed between eachbonding pad 203 and BCB material portions of the BCB materialbonding-insulating layer 205 that immediately neighbor the bonding pad203. During Cu—Cu bonding in the process of combining two wafers, thegaps/recesses 206 may accommodate overflowing Cu, such that unwantedelectrical connections (or short circuits) may be prevented.

The formation of the openings 207 may include the following steps:forming a mask material layer that includes at least one of a firstphotoresist layer, an organic distribution layer (ODL), and asilicon-containing bottom antireflective coating (Si-BARC) on the BCBmaterial layer 204; forming a patterned photoresist layer on the maskmaterial layer, wherein a pattern (e.g., openings) of the patternedphotoresist layer may define the shape(s) of the opening 207; etchingthe mask material layer through the pattern of the patterned photoresistlayer to form a mask; and etching the BCB material layer 204 using themask to form the openings 207.

The shape(s) and/or the number of the openings 207 may be determinedaccording to particular embodiments. In an embodiment, the criticaldimension of the upper portion of an opening 207 may be equal to thecritical dimension of the lower portion of the opening.

The openings 207 may be formed through a dry etching method and/or a wetetching method. In an embodiment, a CF etchant may be used for etchingthe BCB material layer 204. The C—F etchant may include one or more ofCF₄, CHF₃, C₄F₈, and C₅F₈. In an embodiment, dry etching may beperformed using CF₄, CHF₃, and at least one of N₂, CO₂, and O₂ to forman etching atmosphere, with the following gas flow rates: a CF₄ flowrate in a range of 10 sccm to 200 sccm, a CHF₃ flow rate in a range of10 sccm to 200 sccm, a N₂, CO₂, and/or O₂ flow rate in a range of 210sccm to 400 sccm. The etching pressure may be in a range of 30 mTorr to150 mTorr. The etching time duration may be in a range of 5 seconds to120 seconds. In an embodiment, the etching time duration may be in arange of 5 seconds to 60 seconds. In an embodiment, the etching timeduration may be in a range of 5 seconds to 30 seconds. A plurality ofopenings 207 may be formed substantially simultaneously.

Subsequently, referring to FIG. 6 and FIG. 4D, in step 610, thestructure illustrated in FIG. 4D may be cleaned to remove oxides (e.g.,a copper oxide) from the surface of the structure (e.g., the surfaces ofthe bonding pads 203). As a result, a first wafer may be prepared. Asecond wafer may be prepared using steps analogous to steps 601 to 610.The wafers may be prepared substantially simultaneously.

Subsequently, referring to FIG. 6 and FIG. 5A, in step 611, the firstwafer and the second wafer may be combined. The combination of thewafers may involve bonding the BCB material bonding-insulating layer 205of the first wafer with the BCB material bonding-insulating layer 205 ofthe second wafer. The combination of the wafers may further involvesubsequently bonding the bonding pads 203 of the first wafer with thebonding pads 203 of the second wafer. Each of the bonding pads 203 maybe positioned between two neighboring BCB material portions of at leasta BCB material bonding-insulating layer 205.

The bonding of the BCB material bonding-insulating layer 205 of thefirst wafer with the BCB material bonding-insulating layer 205 of thesecond wafer may involve application of a substantial high pressure onat least one of the wafers toward the other wafer at a temperature in arange of 100° C. to 150° C. for a time duration in a range of 10 minutesto 30 minutes. The pressure may be in a range of 10 kN to 100 kN. In anembodiment, the pressure may be in a range of 30 kN to 60 kN.

After the bonding of the BCB material bonding-insulating layers 205, alow pressure may be applied on at least one of the wafers toward theother wafer for bonding the bonding pads 203 of the first wafer with thebonding pads 203 of the second wafer at a temperature in a range of 300°C. to 400° C. for a time duration in a range of 20 minutes to 60minutes. The pressure may be in a range of 20 kN to 50 kN. In anembodiment, the pressure may be in a range of 30 kN to 40 kN. The lowpressure may prevent excessive deformation and/or conductive material(e.g., Cu) overflow of the bonding pads 203. As a result, a wafercombination may be formed.

Subsequently, referring to FIG. 6, in steps 612, annealing may beperformed on the wafer combination. The annealing may be performed at aat a temperature in a range of 300° C. to 800° C. for a time duration ina range of 30 minutes to 90 minutes. The annealing may be performedusing at least one of pulsed laser rapid thermal annealing, pulsedelectron beam rapid thermal annealing, ion beam rapid thermal annealing,continuous-wave laser rapid thermal annealing, and incoherent broadbandlight source (e.g., at least one of a halogen lamp, an arc lamp, andgraphite heating) rapid thermal annealing, etc. The annealing method maybe selected according to particular embodiments.

In an embodiment, a silicone-polymer material may be used instead of theaforementioned BCB material. For bonding silicone-polymer materialbonding-insulating layers of two wafers, the temperature may be in arange of 150° C. to 180° C., the pressure may be in a range of 30 kN to60 kN, and the time duration may be in a range of 10 minutes to 30minutes.

The silicone-polymer material may have the following chemical formula:

In the chemical formula, the R₁ may be an aromatic hydrocarbon, such asone or more of benzene, toluene, o-xylene, m-xylene, p-xylene,ethylbenzene, n-propylbenzene, cumene, biphenyl, naphthalene, etc.and/or one or more associated derivatives. The R₂ may be an alkanehaving a carbon atom count in a range of 1 to 7 and including at leastone of a straight chain and a branch chain. The R₂ may be an aromatichydrocarbon. The composition of R₁ may be identical or different to thecomposition of R₂. The n may be a natural number n is greater than 1.The molecular weight of the silicone-polymer material may be in a rangeof 5,000 to 800,000.

FIG. 5B shows schematic cross-sectional views that illustrate portionsof two wafers involved in a wafer-level Cu—Cu bonding process inaccordance with an embodiment of the present invention. Referring toFIG. 5B and FIG. 6, a first wafer of the two wafers, e.g., the lowerwafer illustrated in FIG. 5B, may be prepared using one or more of steps601 to 610 discussed with references to FIG. 6. Referring to FIG. 5B andFIG. 2, a second wafer of the two wafers, e.g., the upper waferillustrated in FIG. 5B, may be prepared using one or more stepsdiscussed with reference to FIG. 2. During respective wafer preparation,a bonding-insulating material layer (e.g., a BCB material layer) and asubsequent bonding-insulating layer (e.g., a BCB materialbonding-insulating layer 205) may be formed on only one of the twowafers, e.g., the lower wafer.

The prepared first wafer may include bonding pads 203 and abonding-insulating layer (e.g., a BCB bonding-insulating layer 205) thatsurrounds the bonding pads 203. Gaps are provided between the bondingpads 203 and the BCB bonding-insulating layer 205.

The prepared second wafer may include bonding pads 203 and an interlayerdielectric layer 202 surrounding the bonding pads 203, without includinga BCB material layer.

The process of combining the first wafer with the second wafer mayinclude bonding the BCB bonding-insulating layer 205 of the first waferwith the dielectric layer 202 of the second wafer. The BCB material mayhave substantially desirable adhesion with the oxide material of thedielectric layer 202. The bonding may involve application of asubstantial high pressure on at least one of the wafers toward the otherwafer at a temperature in a range of 100° C. to 150° C. for a timeduration in a range of 10 minutes to 30 minutes. The pressure may be ina range of 10 kN to 100 kN. In an embodiment, the pressure may be in arange of 30 kN to 60 kN.

In an embodiment, a silicone-polymer material may be used instead of theaforementioned BCB material. For bonding the silicone-polymer materialbonding-insulating layer of the first wafer with the dielectric layer202 of the second wafer, the temperature may be in a range of 150° C. to180° C., the pressure may be in a range of 30 kN to 60 kN, and the timeduration may be in a range of 10 minutes to 30 minutes.

After the bonding of the bonding-insulating layer 205 with thedielectric layer 202, a low pressure may be applied on at least one ofthe wafers toward the other wafer for bonding the bonding pads 203 ofthe first wafer with the bonding pads 203 of the second wafer at atemperature in a range of 300° C. to 400° C. for a time duration in arange of 20 minutes to 60 minutes. The pressure may be in a range of 20kN to 50 kN. In an embodiment, the pressure may be in a range of 30 kNto 40 kN. The low pressure may prevent excessive deformation and/orconductive material (e.g., Cu) overflow of the bonding pads 203. As aresult, a wafer combination may be formed.

Steps additional to and/or alternative to the steps discussed withreference to FIG. 2 and FIG. 6 may be performed in accordance withembodiments of the invention.

Embodiments of the invention may be related to semiconductor devicesmanufactured using one or more steps discussed with references to one ormore of FIG. 2 to FIG. 6 and/or alternative or additional steps (e.g.,cutting a wafer combination to obtain separated semiconductor devices).

Referring to at least one of FIG. 5A and FIG. 5B, an embodiment of theinvention may be related to a semiconductor device that may include afirst substrate (e.g., a first semiconductor substrate 201) and a secondsubstrate (e.g., a second semiconductor substrate 201). Thesemiconductor device may further include a first conductive pad and asecond conductive pad each being a combination of two conductive pads203 and each being positioned between the first substrate and the secondsubstrate. The semiconductor device may further include a firstdielectric layer 202 formed of a first material (e.g., an oxide), afirst portion of the first dielectric layer being positioned between thefirst conductive pad and the second conductive pad and directlycontacting each of the first conductive pad and the second conductivepad. The semiconductor device may further include a second dielectriclayer 202, a first portion of the second dielectric layer beingpositioned between the first conductive pad and the second conductivepad and directly contacting each of the first conductive pad and thesecond conductive pad. The semiconductor device may further include aninsulating layer formed of a second material different from the firstmaterial, a first portion of the insulating layer being positionedbetween the first portion of the first dielectric layer and the firstportion of the second dielectric layer and being positioned between thefirst conductive pad and the second conductive pad. The insulating layermay represent a combination of two insulating layers 205 illustrated inFIG. 5A or may represent the insulating layer 205 illustrated in FIG.5B. The second material may include at least one of a benzocyclobutenematerial and a silicone-polymer material. The first portion of theinsulating layer may be narrower than the first portion of the firstdielectric layer in a direction parallel to an interface between theinsulating player and the first dielectric layer. The first portion ofthe insulating layer may be spaced from all conductive pads of thesemiconductor device.

An edge portion of the insulating layer may be positioned at an edge ofthe semiconductor device, may directly contact each of an edge portionof the first dielectric layer and an edge portion of the seconddielectric layer, and may be narrower than the edge portion of the firstdielectric layer in a direction parallel to an interface between theinsulating layer and the first dielectric layer. The edge portion of theinsulating layer may be spaced from all conductive pads of thesemiconductor device.

According to embodiments of the invention, the bonding-insulating layer205 may substantially enhance bonding force and bonding areas betweenthe wafers, such that satisfactory structural robustness may beadvantageously provided. The bonding-insulating layer 205 may alsoprevent unwanted diffusion and electrical connections between bondingpads 203, such that satisfactory device quality and performance may beadvantageously provided.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents, which fall withinthe scope of this invention. It should also be noted that there are manyalternative ways of implementing the methods and apparatuses of thepresent invention. Furthermore, embodiments of the present invention mayfind utility in other applications. The abstract section is providedherein for convenience and, due to word count limitation, is accordinglywritten for reading convenience and should not be employed to limit thescope of the claims. It is therefore intended that the followingappended claims be interpreted as including all such alterations,permutations, and equivalents as fall within the true spirit and scopeof the present invention.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, the method comprising: providing a first dielectric layer and afirst set of conductive pads on a first substrate, each conductive padof the first set of conductive pads being positioned between portions ofthe first dielectric layer; providing a first insulating material layerto cover the first dielectric layer and the first set of conductivepads; and removing portions of the first insulating material layer toform a first insulating layer, opening of the first insulating layerexposing the first set of conductive pads.
 2. The method of claim 1,wherein the first insulating layer includes at least one of abenzocyclobutene material and a silicone-polymer material.
 3. The methodof claim 1, further comprising: forming a first dielectric materiallayer on the first substrate; and etching the first dielectric materiallayer to form the first dielectric layer, wherein a thickness of thefirst dielectric layer is less than a thickness of the first dielectricmaterial layer.
 4. The method of claim 1, wherein the first insulatingmaterial layer is formed on the first dielectric layer and the first setof conductive pads through spin coating.
 5. The method of claim 1,wherein the openings includes a first opening, wherein the first set ofconductive pads includes a first conductive pad exposed by the firstopening, wherein a critical dimension of the first opening of the firstinsulating layer is greater than a critical dimension of the firstconductive pad, such that a first gap is provided between the firstconductive pad and the first insulating layer.
 6. The method of claim 1,wherein the first insulating layer does not directly contact the firstset of conductive pads.
 7. The method of claim 1, wherein a firstportion of the first insulating layer is positioned between at least twoconductive pads of the first set of conductive pads, wherein a secondportion of the first insulating layer directly contacts an edge portionof the first dielectric layer, wherein at least one conductive pad ofthe first set of conductive pads is positioned between the first portionof the first insulating layer and the second portion of the firstinsulating layer, and wherein the second portion of the first insulatinglayer is narrower than the edge portion of the first dielectric layer ina direction parallel to an interface between the first insulating layerand the first dielectric layer.
 8. The method claim 1, wherein theremoving the portions of first insulating material layer comprises:forming a mask material layer on the first insulating material layer,the mask material layer including at least one of a first photoresistlayer, an organic distribution layer, and a silicon-containing bottomantireflective coating; forming a patterned photoresist layer on themask material layer; etching the mask material layer using the patternedphotoresist layer to form a mask; and etching the first insulatingmaterial layer using the mask.
 9. The method of claim 1, wherein aheight of the first insulating layer with respect to the first substrateis greater than a height of the first set of conductive pads withrespect to the first substrate.
 10. The method of claim 1, furthercomprising: providing a second dielectric layer and a second set ofconductive pads on a second substrate, each conductive pad of the secondset of conductive pads being positioned between portions of the seconddielectric layer; providing a second insulating material layer to coverthe second dielectric layer and the second set of conductive pads; andremoving portions of the second insulating material layer to form asecond insulating layer, opening of the second insulating layer exposingthe second set of conductive pads; connecting the first insulating layerto the second insulating layer; and after the connecting the firstinsulating layer to the second insulating layer, connecting the firstset of conductive pads to the second set of conductive pads.
 11. Themethod of claim 10, wherein at least one of the first insulating layerand the second insulating layer is formed of benzocyclobutene, andwherein the connecting the first insulating layer to the secondinsulating layer is performed at a temperature in a range of 100° C. to150° C. for a time duration in a range of 10 minutes to 30 minutes usinga pressure in a range of 30 kN to 60 kN.
 12. The method of claim 10,wherein at least one of the first insulating layer and the secondinsulating layer is formed of a silicone-polymer material, and whereinthe connecting the first insulating layer to the second insulating layeris performed at a temperature in a range of 150° C. to 180° C. for atime duration in a range of 10 minutes to 30 minutes using a pressure ina range of 30 kN to 60 kN.
 13. The method of claim 10, wherein theconnecting the first set of conductive pads to the second set ofconductive pads is performed at a temperature in a range of 300° C. to400° C. for a time duration in a range of 20 minutes to 60 minutes usinga pressure in a range of 30 kN to 40 kN.
 14. The method of claim 1,further comprising: providing a second dielectric layer and a second setof conductive pads on a second substrate, each conductive pad of thesecond set of conductive pads being disposed between portions of thesecond dielectric layer; connecting the first insulating layer to thesecond dielectric layer; and after the connecting the first insulatinglayer to the second dielectric layer, connecting the first set ofconductive pads to the second set of conductive pads.
 15. The method ofclaim 14, wherein the first insulating layer is formed ofbenzocyclobutene, and wherein the connecting the first insulating layerto the second insulating layer is performed at a temperature in a rangeof 100° C. to 150° C. for a time duration in a range of 10 minutes to 30minutes using a pressure in a range of 30 kN to 60 kN.
 16. The method ofclaim 14, wherein the first insulating layer is formed of asilicone-polymer material, and wherein the connecting the firstinsulating layer to the second insulating layer is performed at atemperature in a range of 150° C. to 180° C. for a time duration in arange of 10 minutes to 30 minutes using a pressure in a range of 30 kNto 60 kN.
 17. A semiconductor device comprising: a first conductive pad;a second conductive pad; a first dielectric layer formed of a firstmaterial, a first portion of the first dielectric layer being positionedbetween the first conductive pad and the second conductive pad anddirectly contacting each of the first conductive pad and the secondconductive pad; a second dielectric layer, a first portion of the seconddielectric layer being positioned between the first conductive pad andthe second conductive pad and directly contacting each of the firstconductive pad and the second conductive pad; and an insulating layerformed of a second material different from the first material, a firstportion of the insulating layer being positioned between the firstportion of the first dielectric layer and the first portion of thesecond dielectric layer and being positioned between the firstconductive pad and the second conductive pad.
 18. The semiconductordevice of claim 17, wherein the first portion of the insulating layer isnarrower than the first portion of the first dielectric layer in adirection parallel to an interface between the insulating player and thefirst dielectric layer.
 19. The semiconductor device of claim 17,wherein the second material includes at least one of a benzocyclobutenematerial and a silicone-polymer material.
 20. The semiconductor deviceof claim 17, wherein an edge portion of the insulating layer ispositioned at an edge of the semiconductor device, directly contactseach of an edge portion of the first dielectric layer and an edgeportion of the second dielectric layer, and is narrower than the edgeportion of the first dielectric layer in a direction parallel to aninterface between the insulating layer and the first dielectric layer.